(Above) Master craftsman Martin O'Connor inspects one of the 32 newly carved heads on the Chapter House at Westminster Abbey

More than a year after craftsmen began a £3 million mission to restore the original Medieval home of politics, Westminster Abbey’s ancient Chapter House will mark the formation of Britain's new parliament by reopening tomorrow to reveal the painstaking efforts of 20 master craftsmen and stonemasons who have reimagined the dilapidated building.

Constructed at some point during the mid-13th century, the East Cloister chamber was lauded as "beyond compare" when it served as the daily meeting point for dozens of monks of Westminster Abbey, also providing a key venue for Henry VIII's Great Council and Commons.

Stone carvers from English Heritage's project team and the Westminster Abbey clergy have replaced Victorian heads on the building which had become unstable due to erosion

By the mid-19th century such praise had become a sadly distant memory, and a high-profile campaign to save it resulted in noted architect George Gilbert Scott transforming it in a formidably intricate Victorian style, complete with tiled floors and wall paintings.

Despite being recognised as a historic public monument, it became jaded by decades of smoke from nearby Battersea power station, traffic pollution and the weather, reported in the Guardian as "painfully clear" signs of decay.

The team describe the newly-renovated House as "weather-tight"

English Heritage, who maintain the building for the Crown, undertook the campaign to clean and repair gargoyles and stained glass windows, and the dismantlement of their "colossal" scaffolding façade will unveil 32 stone faces, carved by masons in line with Scott's designs.

Four new gargoyles have been introduced, adding to the total swathe of 64 heads across eight pinnacles.

A newly-conserved stone monkey hangs from one of the gargoyles nodding to the original Victorian sculpture of the building

"The Chapter House is a remarkable building and a very significant part of the 13th century monastic enclosure," said The Very Reverend Dr John Hall, Dean of Westminster.

"It now once again looks strikingly beautiful as a result of the initiative and excellent work of English Heritage."

Badly-weathered gargoyles, stone floral friezes, flying buttresses and stained glass windows were among the features needing repair when the team stepped in 18 months ago

English Heritage's Simon Thurley called the House "one of England'smost interesting and significant monuments."

"The Chapter House is witness to great events in our early history and repository of the nation's history and memories for 300 years," he added.

"I'm proud to say that English Heritage has been able to secure its future with one of our most comprehensive programmes of conservation ever."